Various abbreviations are used in the present specification. These are listed and explained towards the end of the description.
Mobile CS services based on GSM and WCDMA radio access are widely used and allow obtaining telecommunication services with a single subscription in almost all countries of the world. The number of CS subscribers is still growing rapidly, in particular in dense population countries such as India and China. This success is furthermore extended by the evolution of the classical MSC architecture into a softswitch solution which allows using packet transport infrastructure for mobile CS services.
The 3GPP work item “Evolved UTRA and UTRAN” (started in summer 2006) has defined a Long-Term Evolution (LTE) concept that assures competitiveness of 3GPP-based access technology. It was preceded by an extensive evaluation phase of possible features and techniques in the RAN workgroups that concluded that the agreed system concepts can meet most of the requirements and no significant issue was identified in terms of feasibility.
It is envisaged that LTE will use OFDM radio technology in the downlink and SC-FDMA for the uplink, allowing at least 100 Mbps peak data rate for downlink data rate and 50 Mbps for uplink data rate. LTE radio can operate in different frequency bands and is therefore very flexible for deployment in different regions of the world.
In parallel to the RAN standardization 3GPP also drives a System Architecture Evolution (SAE) work item to develop an evolved core network. The SAE core network is made up of core nodes, which are further split, according to a proposal by Ericsson, into Control Plane (MME (1)) and User Plane (AGW (2)) nodes. In the terminology currently used AGW-UP contains both User Plane Entity (UPE) and Inter-Access Anchor (IASA) functionality. The MME is connected to the eNode B (3) via the S1-MME interface and the AGW is connected to the eNode B (3) via the S1-UPE interface. This is illustrated in FIG. 1.
Common to both, LTE and SAE is that only a Packet Switched (PS) domain will be specified, i.e. all services are to be supported via this domain. GSM (via Dual Transfer Mode DTM) and WCDMA however provide both PS and CS access simultaneously. While the mobile CS service penetration is still increasing world-wide, there is no support planned in standards for using these mobile CS telephony (MSS) solutions via an LTE radio access (6) or via the SAE based core network. As FIG. 2 shows, there is no connection between LTE radio (6) and Classic CS (13).